The present invention relates to a bushing which receives a pin, and more particularly to a bottom plate inside the bushing beneath the bottom end of the pin. Such a bushing and pin combination may be used for the pin of a cross piece of a universal joint, although it is not limited to this.
The pin inside the bushing has a bottom end which is the end that extends into the open receptacle of the bushing. The bushing has a peripheral side wall and a bottom which defines the receptacle for the end of the pin. Where the pin is movable relative to the bushing, as in a universal joint, a set of rolling elements or rollers, usually cylindrical rollers, are disposed around the pin, with their axes parallel to the pin axis, for rolling engagement between the pin and the interior wall of the bushing, at the bottom end of the pin. Lubrication of such a pin-in-bushing combination is desirable, and this can be accomplished quite well through a well-designed bottom plate between the bottom end of the pin and the bottom of the bushing.
A bottom plate for a bushing that is disposed over the end of a pin is known from Federal Republic of Germany Utility Model No. 70 35 694. Such a bushing may be disposed on the pin of a universal joint, for example. The bottom plate shown there is provided on both of its sides with lubricating grooves, whereby sufficient lubrication can come into the region of the peripheral wall of the bushing. But, an additional part is still necessary, namely a cup spring which urges the rollers at their upper axial ends toward the bottom of the bushing. Upon relubrication of the bushing, the lubricant, taking the path of least resistance, will probably pass through the grooves which are located between the end of the pin and the bottom plate. It then enters the region of the wall of the bushing and into the space containing the rolling elements, but only if a cup spring is provided. The grooves which are located on the rear soon become closed as this represents the longer path. Furthermore, there is no relative movement here between the bottom plate and the bottom of the bushing. This stationary condition favors closure at this place.